1. Field of the Invention
The present invention relates to a mold structure provided with a pattern of concavities and convexities for transferring information onto a magnetic recording medium, in particular a mold structure for nanoimprinting.
2. Description of the Related Art
In recent years, hard disk drives that are superior in reading and writing swiftness and costs have begun being incorporated in portable devices such as cellular phones, compact acoustic devices and video cameras as major storage devices, and a technique for improving recording density has been required to meet the demand for further reduction in size and enlargement in capacity.
In order to increase the recording density of hard disk drives, methods such as improvement in the performance of magnetic recording media and reduction in the magnetic head width have been conventionally used; however, as spaces between data tracks are made small, effects of magnetism between adjacent tracks (crosstalk) and effects of heat fluctuation become inevitably great, hence a limitation on improvement in surface recording density by means of the narrowing of magnetic heads or the like.
Accordingly, magnetic recording media in a form referred to as discrete track media have been proposed as a means of removing noise caused by crosstalk (refer to Japanese Patent Application Laid-Open (JP-A) Nos. 56-119934 and 02-201730).
In discrete track media, magnetic interference between adjacent tracks is reduced by means of discrete structures in which nonmagnetic guard band regions are provided between adjacent tracks so as to magnetically separate tracks from one another.
Also, magnetic recording media in a form referred to as patterned media, in which bits for recording signals are provided in predetermined patterns of shape have been proposed as a means of removing demagnetization caused by heat fluctuation (refer to JP-A No. 03-22211).
As a method for producing the discrete track media and the patterned media, there is an imprinting method in which a desired pattern is transferred onto a resist layer formed on a surface of a magnetic recording medium by using a resist pattern forming mold (hereinafter otherwise referred to as “mold”), as disclosed in JP-A No. 2004-221465.
However, as to a resist pattern forming mold described in JP-A No. 2004-221465, since convex portions formed on a surface thereof are shaped like rectangles in cross-section, it is impossible to push out a resist layer sufficiently when the mold is pressed against the resist layer and thus impossible to obtain an appropriate resist pattern; consequently, the convex portions of the mold structure may possibly vary in height. This is a phenomenon which can also arise when the convex portions pressed against the resist layer are separated from the resist layer.
Thus, a mold structure capable of efficiently transferring a pattern to a resist layer applied onto a substrate of a magnetic recording medium has not yet been realized, and provision of the mold structure is hoped for, as things stand.